(a) Field of the Invention
The invention relates to a control method of a traffic sign, particularly to a control method of a traffic sign by utilizing a vehicular network.
(b) Description of the Related Art
In general, a method of controlling a traffic sign usually controls every constant period of time and thus it cannot adjust dynamically according to the present traffic flow. On the other hand, an adjustable sign utilizes a detector to detect a live traffic flow. For example, an induction coil, magnetic sensor or roadside video recognition technology can be used.
Currently, a system utilizing a wireless sensor network (WSN) needs sensors and a RFID (Radio-frequency identification)-based system needs RFID readers installed in every section. Thus, hardware build-up cost is high. Besides, many problems still exist. First, the traffic flows with longer queues may have lower passing rates than those with shorter queues. Second, the existing approach may cause starvation to shorter queues. Thirdly, some lanes may have mixture of straight-going and right/left-turning vehicles. Furthermore, since each section usually includes a shared right turn lane, vehicles going straight may be blocked by vehicles turning right or vice versa. Especially, such a traffic flow mixing vehicles going straight and turning right causes the decrease in traffic volume.